A biaryl compound is an extremely important compound as various chemical products and intermediates for synthesis of them. It is generally known that a biaryl compound can be produced by Suzuki coupling reaction using aryl boric acid, a reaction using a nickel catalyst and a Grignard reagent, Ullmann reaction using aryl iodide, or the like (e.g. Comprehensive Organic Synthesis, 3, 499 (1991) etc.). However, all these methods use an expensive reagent, ligand or catalyst and, therefore, further improvement has been desired from an industrial point of view.
On the other hand, as a process for producing a biaryl compound without an expensive reagent, ligand or catalyst such as the above-mentioned reagent, ligand or catalyst, there was proposed a method comprising reaction of an arylhydrazine compound, an oxidizing agent and an aryl compound. For example, methods using, as an oxidizing agent, (1) silver oxide (J. Chem. Soc., 2512 (1957)), (2) manganese acetate (J. Chem. Soc. Perkin Trans. 1, 3042(2001)), (3) mercury oxide (Liebigs Ann. Chem., 199, 332(1879)), (4) barium ferrate (Bull. Chem. Soc. Jpn., 61, 2185(1988)), (5) lead acetate (J. Chem. Soc. (C), 1663(1969)) and (6) potassium superoxide (Aust. J. Chem., 37, 2499 (1984)) respectively were reported. However, all the above-mentioned oxidizing agents are relatively expensive and moreover, may be toxic or be difficult to handle after reaction. Therefore, development of an industrially more advantageous method has been desired.